Art of detecting oscillations.



1170. 867,877. PATENTEDOGT.8, 1007.

L. DE FOREST.

ART OF DETECTING OSCILLATIONS.

APPLICATION FILED JUNE 12. 1007.

Fig.1. 7 Fig-2- c avi UNITED OFFICE.

LEE DE FOREST, OF NEW YORK, N. Y., ASSIGNOR TO GEORGE K. WOODWORTH, OlBOSTON, MASSACHUSETTS.

ART OF DETECTING OSCILLATIONS.

Specification of Letters Patent.

Original application filed February 2, 1905, Serial No. 243,9 13.Divided and this application Serial No- 378,503.

Patented Oct. 8, 1907.

filerl June 12, 1907.

To all whom it may concern:

Be it known that 1, Lee on Fonns'r, a citizen of the United States, anda resident of New York, in the county of New York and State of New York,have invented a new and useful Improvement in the Art of DetectingOscillations, of which the following is a specification.

My invention relates to an improvement in the art oi receiving wirelesstelegraph signals transmitted from a distaut station by means ofelectrical waves.

In the drawings which accompany and iorm'a part of the presentspecification I have shown several forms of apparatus and circuitarrangements whereby my method may be carried into effect; but it willbe understood that my invention is broader than mere. apparatus and thatmy method mayv he carried into effect by a great variety of apparatus.

In the drawings, Figures 1., 2, 3, 4 and 5 represent space telegraphreceiving systems.-

In the-figures, A represents an antenna or receiving conductor, orwave-intercepting means; E is the earth connection; F, F, F F F, F arethe electrodes in their various forms; B is the local battery; and T isthe receivingor indicating instrument which is herein shown as atelephone receiver, the same being shown only as typical of any form ofindicating apparatus capable of being employed for such purposes.

I have discovered that if two bodies adapted for use as electrodes orconductive members be electrically separated partially or wholly, afterthe manner common in analogous devices, the separation between them maybe neutralized sufficiently to enable them to act as a detector ofelectrical oscillations, if the intervening or surrounding gaseousmedium be put into a condition of molecular'and ionic activity, such forinstance as would be caused by heating it in-any mannor, as byradiation, conduction, or by the combustion of gases in the space whichsurrounds the electrodes.- Such condition of molecular and ionicactivity causes what would otherwise be a non-sensitive device to hecomesensitive to the reception of electrical influences. I am thus enabledto employ as such sensitive member, devices which would otherwise be ofno value and which comprise electrodes separated by a gaseous medium.This principle-is embodied in the apparatus illustrated in the variousfigures shown.

' In Fig. 1 the two electrodes F, F are slightly separated and arewithin the flame of an ordinary Bunsen burner D. Under these conditionsthe electrodes may be adjusted so that there is normally no indicationof a passing current given by the receiving instrument, such as thetelephone T. The electrical separation of the electrodes is, however,insuilicient to prevent electrical oscillations from passing across thegap. The influence of these oscillations upon the heated gas seems tovary the insulating quality of the gap, so that, while the influence oithe oscillations lasts the current of the local circuit may pass betweenthe electrodes, thus affecting the indicating instrument therein toproduce a signal. This may be due to ionization of the gases surroundingthe electrodes which greatly increases their conductivity, saidionization being more or less accomplished or greatly facilitated in thepresent instance by their previous heating which has alreadyput them ina condition oi intense molecular activity.

In Fig. 2, the electrodes F F are of sufficiently great resistance to beheated-by a current from a dy-- name G, and by their radiation heat thegas between them. This gas may be air or the electrodes may be inclosedand surrounded by any suitable gas.

In Fig. 3 the electrodes assume the form of two parallel plates F F",which are heated by a Bunsen burner. Although I have showna Bunsenburner for this purpose, this particular heating device is notessential, as any means of heating may be employed.

In Fig. 4, the burner itself is made. one of the electrodes, the otherof which is shown at F.

In Fig. 5 the local circuit is provided with electrodes I F and theoscillation-receiving circuit with separate electrodes F F both beingheated by the lame of the Bunsen burner. The effect in this case is thesame as before stated, that is, the passage of the oscillations enablesthe current of the local circuit to jump the gap between the electrodesF F and thus to operate the receiving instrument. The oscillationsapparently ionize the gas and thus temporarily reduce its insulatingpower, or, in other words, increase its conductivity and enable thecurrent of the local circuit to overcome the resistance between itspoles.

The action described may be effected by controlling the composition ofthe gases between and surrounding the electrodes or poles of thesensitive member. As an instance of this, the addition of sodium orsalts of the halogen class in the flame increases the ionization andconductivity of the gases and increascs the sensitiveness of the device.

While I have shown and described various means for realizing my methodin practice, I am aware that not all the possible means have been shownand described. Sufficient information, however, has been herein setforth to enable any one skilled in this art to carry out my method,which broadly stated consists in receiving wireless telegraph signals bycausing the electrical oscillations developed in a wireless telegraphreceiving system to vary the conductivity of a gas maintained inacondition of intense molecular and ionic activity and havingdissociated and conducting ions.

' I make no claim herein'to the apparatus and circuit magnetic signalwaves, the method herein described which consists in establishing in acircuit a gaseous medium maintained in a condition of molecular andionic activity, impressing the electrical oscillations resulting fromthe waves to be received upon said gaseous medium and thereby alteringthe electrical condition of the circuit of whiclrsaid gaseousmediumforms a part, and translating the resulting current variations intosignal indications.

2. As an improvement in the art of receiving electromagnetic signalwaves, the method'herein' described which consists in establishing in acircuit a gas having dissociated and conducting ions, altering by theenergy of the electrical oscillations resulting from the waves to bereceived, the conductive properties of said gas, and translating theresulting current variations into slgnni indi cations.

3. As an improvement in the art 01. receiving electronmgnetic signalwaves, the method herein described which consists in causing theelectrical oscillations developed by electromagnetic waves in a wirelesstelcgruph receiving system to vary the electrical conductivity of a gasmaintained in a. condition of intense molecular and ionic activity andhaving dissociated and conducting ions, and translating the resultingcurrent variations into signal indications.

4. As an improvement in the art of receiving electromagnetic signalwaves, the method herein described which consists in absorbing theenergy of said waves. impressing LEE DE FOIEICSI.

Witnesses ii. W. Gon'rzn, Tnouss I. (innnmunn.

